An image forming apparatus, such as a copying machine, a printer, a facsimile machine, or a multifunction machine reads image data from an image reading apparatus or receives image data from a network. The image data can be temporarily stored into non-volatile storage apparatus having large a storage capacity, such as a hard disk drive. The image data stored in the non-volatile storage apparatus is read out, and a predetermined image processing operation is carried out such as, for example, formatting the images for printing.
Once the image data is read out, the image data on the non-volatile storage apparatus can be overwritten. In certain environments, such as high security environments, it is desirable to overwrite the image data so that it cannot be recovered by a third party once it is read out. Known methods for overwriting image data, however, typically involve overwriting the image data with fixed overwrite patterns.
Unfortunately, these overwrite patterns can be discovered and the image data can then be recovered from the non-volatile storage apparatus. Thus, there is a risk that sensitive image data can be recovered from the image forming apparatus using known overwrite methods.
Accordingly, it would be desirable to provide an image forming apparatus that securely overwrites image data. It may also be desirable to provide an image forming apparatus that overwrites its image data in a manner that prevents subsequent recovery.